1. Field
The present disclosure relates to a circuit and a method for temperature compensation of a sensor, and more particularly to a circuit and a method for temperature compensation of a sensor which perform compensation for output variation generated due to change of an environment temperature.
2. Related Art
With the advance of science and technology, more and more sensors are designed and developed. There are various sensors, such as pressure sensors, temperature sensors, gas sensors, sound sensors, brightness sensors, speed sensors, and image sensors. Sensors are also widely used in various fields, such as, medical apparatus, public transportation vehicle, safety detection, entertainment, national defense, and so on.
In the field of pressure sensing, strain gauge, also called strain gage, is broadly used. Linearity is one most important issue of the pressure sensor. Ideally, the output voltage of a Wheatstone bridge with a strain gauge is directly proportional to the pressure received by the strain gauge but independent from temperature. However, it is found that the output voltage of the aforementioned Wheatstone bridge is also a function of temperature.
Furthermore, another important issue of the pressure sensor is the sensitivity. It is required that the pressure sensor may perform at 80° C. as well as at 25° C. However, because of the material characteristic of the pressure sensor, the sensitivity of the pressure sensor varies with temperature.
In such circumstances, a measured result at 25° C. is different from a measured result in 100° C. Such difference may introduce some sensing problems and is an error to be compensated.
In a current system using a sensor, in order to improve preciseness, temperature compensation measures are generally implemented for the sensor for avoiding the problems caused from the variation of the environment temperature. The measures include two types: (1) by use of a hardware line to perform temperature compensation, and (2) by use of a hardware line in cooperation with software temperature compensation. The two types are respectively described as follows:
(1) By use of a hardware line to perform temperature compensation:
In the amplifier circuit connecting behind the sensor output terminal, elements having temperature features such as a thermistor or temperature sensor are added to the loop of the amplifier circuit to automatically adjust the gain factor.
(2) By use of a hardware line in cooperation with the software temperature:
Elements having temperature features such as a thermistor or temperature sensor are added to the system to sense the environment temperature, and then the processor circuit compensates the temperature offset.
However, the two temperature compensation manners for the conventional sensor both have disadvantages. First, the circuit structure of the former one is complex and requires correction; and although the circuit structure of the latter one is simple, the offset needs to be corrected for each temperature point, which is very time-consuming.
For these reasons, it is desirous to provide a circuit and a method for temperature compensation of a sensor performing compensation for the output variation generated due to the change of the environmental temperature so as to avoid deficiency of the temperature compensation manners for the conventional sensor.